Interaction effects in non-equilibrium transport properties of a four-terminal topological corner junction

TL;DR

This paper investigates the complex transport behaviors in a four-terminal topological insulator junction, revealing how inter-boundary tunneling and Coulomb interactions influence current and noise characteristics beyond linear response.

Contribution

It introduces a theoretical framework combining scattering field theory and mean-field approximation to analyze interaction effects in topological corner junctions.

Findings

Identification of signatures of Coulomb blockade in transport properties.

Analysis of current fluctuations and noise beyond linear response.

Discussion of universal thermal noise features in helical topological systems.

Abstract

We study the transport properties of a four-terminal corner junction made by etching a two- dimensional topological insulator to form a quantum point contact (QPC). The QPC geometry enables inter-boundary tunneling processes allowing for the coupling among states with different helicity, while the tight confinement in the QPC region activates charging effects leading to the Coulomb blockade physics. Peculiar signatures of these effects are theoretically investigated using a scattering field theory modified to take into account the electron-electron interaction within a self- consistent mean-field approach. The current-voltage characteristics and the current fluctuations (noise) are derived beyond the linear response regime. Universal aspects of the thermal noise of the corner junction made of helical matter are also discussed.